1. Field of the Invention
This invention relates to the nozzle assembly of a constant fine lubrication device.
2. Description of the Prior Art
In recent years, there has been a trend toward very high the rotational speeds of the spindles of machine tools. Expressing this trend in terms of the so-called dm.multidot.n value (dm: average diameter of bearings, n: number of revolutions), it has heretofore been 300,000-400,000, whereas nowadays dm.multidot.n values exceeding 800,000 are required. However, if the dm.multidot.n value exceeds 800,000, it gives rise to problems such as temperature rise and increased torque and therefore, conventional grease lubrication using grease which is quick in deterioration cannot be used. Besides grease lubrication, forcible lubrication and mist lubrication are known, but they are not free from various problems if the dm.multidot.n value is of the order of 800,000.
Under such circumstances, in recent years, so-called constant fine or very small quantity lubrication has been adopted instead of the above-mentioned lubrication systems. The constant fine lubrication device is a device in which a constant very small quantity of lubricating oil supplied from a constant fine lubricant supplying unit is carried on an air stream and injected from a nozzle to an object to be lubricated.
The constant fine lubrication is such that a very small quantity of lubricating oil of the order of 0.01-0.03 cc/30 min. is constantly supplied to the object to be lubricated and therefore, it is required that no leakage and stagnation of the oil occur in the path leading from the constant fine lubricant supplying unit to the object to be lubricated. For this reason, pipe seams and variations in diameter must be avoided.
However, heretofore, for example, where a bearing is to be lubricated, the distal end of the pipe has been connected to the oil hole of a housing by a joint and lubricating oil has been injected from the oil hole of the housing to the oil hole of an outer race spacer and from a nozzle to the bearing. In this case, there is a gap between the housing and the spacer and there is a difference in diameter between the oil hole of the housing and the oil hole of the outer race spacer and therefore, there has been an undesirable possibility that smooth flow of the lubricating oil is hampered in this portion and the lubricating oil leaks around this portion.